Ch. 9: Intro to microbial genetics Flashcards
Genome
complete set of chromosomes and genes in an organism; plasmids
sum total of all genetic information of cell; DNA divided up into Genes
plasmid
extrachromosomal genetic unit characterized by several features; double-stranded DNA that is smaller than and replicates independently of cell chromosome; bears gene not essential for cell growth; transmissible to other bacteria
genes
site on a chromosome that provides information for a certain cell function; specific DNA segment that necessary code to make protein/ RNA molecule
fundamental unit of heredity that provides a trait to an organism; sections/sequences of DNA within DNA strand
genotype
the genetic makeup of an organism as inherited from parents; responsible for phenotype or expressed characteristics
what types of genes an organism contains; alleles
phenotype
observable characteristics of an organism produced by expression of its genetic potential (Genotype); includes morphological and physiological traits
physical traits/ what does the organism look like?
histones
protein associated with eukaryotic DNA; serve as scaffolding to compact and condense DNA into chromosomes; also enhance or prevent expression of certain genes
nucleosomes
structure in the packaging of eukaryotic DNA formed when the DNA strands wrap around histone proteins, forming an arrangement that looks like beads on a chain
semi-conservative replication
in DNA replication, during synthesis of new DNA strands (the daughter DNA) the parent strand template DNA is retained in the final molecule
produce two copies that each contained one of the original strands of DNA and one new strand. Semiconservative replication is beneficial to DNA repair.
DNA replication
the biological process of producing two identical replicas of DNA from one original DNA molecule.
-DNA replication occurs in all living organisms acting as the most essential part of biological inheritance.
transcription
definition + steps
the process by which a strand of RNA is produced against a DNA template
taking DNA molecule and copying one of its strands into an RNA molecule; if it is mRNA, can be used to make protein
Initiation- RNA polymerase binds to A-T rich region;;; DNA sequence called promoter region; promoter is 5 prime 2; before coding region of gene;;; opens double helix to reveal info inside
—for prokaryotes, RNA polymerase binds by sigma factor, but in euk, determined by variety of factors (diff locations for euks.)
Elongation- RNA polymerase moves along the DNA strand; nucleotides added 1 by 1 based on what complements to DNA template strand to make a long RNA strand; double helix coils and reforms behind RNA polymerase as it moves
Termination sequence- RNA polymerase recognizes a termination site> causes molecular distortion causing RNA polymerase to fall of DNA molecule, releasing RNA molecule, and RNA polymerase can be used again to transcribe
Codon
a sequence of 3 nucleotides in mRNA
-translated into a single amino acid
coding strand
the coding strand is the DNA strand whose base sequence is identical to the base sequence of the RNA transcript produced.
-this strand contains codons, while the non-coding strand contains anticodons.
introns
(eukaryotes only)
a contracted version of “intragenic regions”
Segments on split genes of eukaryotes that do not code for polypeptide; serve other functions
[[[intervening stretches of DNA that are not expressed are called introns]
During transcription, exons are separated from introns and spliced together into a continuous mRNA transcript]]]
exons
(eukaryotes only)
a section of eukaryotic DNA coding for a corresponding portion of mRNA that is translated into proteins
[intervening stretches of DNA that are not expressed are called introns]
During transcription & translation, exons are separated from introns and spliced together into a continuous mRNA transcript
operon
(only in prok/bacteria)
set of more than one gene that makes a single mRNA molecule; regulated together; transcription on or off so genes are all on/expressed or off.
inducible- turn on/increase gene expression (default is off)
OR
repressible- default on, can be shut off
mutations
a permanent inheritable alteration in the DNA sequence or content of a cell
wild-type
the natural, non mutated form of a genetic trait
Epigenetics
study of how cells control gene activity without changing the DNA sequence
study of changes above/beyond nucleotide changes
conjugation
in bacteria, contact between donor and recipient cells associated with transfer of genetic material like plasmids ; can involve special (sex) pili; also form of sexual recombination in ciliated protozoans
transformation
microbial genetics: transfer of genetic material contained in “naked” DNA fragments from a donor cell to a competent recipient cell
transduction
transfer of genetic material from one bacterium to another by means of a bacteriophage vector; accidental
transposons
DNA segment with an insertion sequence at each end, enabling it to migrate to another plasmid, to the bacterial chromosome, or to a bacteriophage
happens in all organisms including our cells… individual DNA pieces that move around on their own inside our cells (some can replicate) they are single, jumping genes. Can move from 1 location to another, sometimes copy themselves, or escape and leave cell… = Mutation or change in DNA = genetic evolution
supercoiling is how:
prokaryotes package DNA
The first enzyme used in DNA replication is:
Gyrase [uncoiling supercoil, to loosen helix]
genetics
study of inheritance; understanding trait a cell gets from parent(s)
Structural Gene
any gene that codes for protein; mRNA translated to make protein
Regulatory genes
just regulate/control other genes; controlling gene expression
around how many genes are in the human genome?
In E coli?
Human- 21,000
Ecoli- around 4,000 [4,288]
what is a nucleotide made of
pentose sugar, nitrogenous base, phosphate group
in the backbone of DNA what kind of bond is it between the phosphate and sugar?
phosphodiester bond
how does phosphate affect the DNA?
makes it negatively charged
Structural genes code for:
cellular proteins.
Eukaryotic chromosomes differ from prokaryotic chromosomes because only eukaryotes have
-elongated linear, not circular, chromosomes.
-several to many chromosomes.
-histone proteins.
-chromosomes in a nucleus.
Among the microorganisms, various genomes can include
plasmids.
chromosomes.
mitochondrial DNA.
chloroplast DNA.
The expression of genetic traits is the
phenotype
The ________ is all of the genetic material of a cell.
genome
A nucleosome is a linear chromosome wound around the:
histone
DNA gyrase function
supercoils DNA.
Okazaki fragments are attached to each other to form a continuous lagging strand by the enzyme:
DNA ligase.
Helicase function
unzips DNA.
DNA polymerase III function
synthesizes new DNA only in the 5’ to 3’ direction.
adding bases to the new DNA chain, proofreading the chain for mistakes
The enzyme that helps pack DNA into the cell by coiling the DNA into a tight bundle is
DNA gyrase.
The duplication of a cell’s DNA is called
replication.
Telomeres are found:
at the ends of linear DNA
for Euk.s, transcription occurs in the:
Translation occurs in the:
nucleus or at the nucleoid.
Cytoplasm or attached to rough ER
During translation elongation, the next tRNA enters into the:
A site
Transcription
process of ______?
Occurs in _______
requires a ___________ strand
requires __________ polymerase
Occurs before ____________
is a process of RNA synthesis.
Occurs in nucleus/nucleoid
requires a template DNA strand [[[strand being copied]]]
requires RNA polymerase.
occurs before translation.
RNA molecules differ from DNA molecules because only RNA
is typically one strand of nucleotides.
does not have thymine.
has ribose.
has uracil.